Metal cutting tools of the kind to which the present invention relates are generally formed with an elongated shaft for mounting on a machine tool turret, the shaft having formed therein a cooling duct. The tool is furthermore provided with means by which cooling liquid is introduced into the duct. The cooling liquid exits from the duct via appropriate apertures so as to be directed onto the work piece. In use therefor, means must be provided for ensuring that the cooling liquid supply conduit is effectively coupled to the shaft. It is known to provide the cooling duct in the region thereof adjacent a rear surface of the tool shaft with screw threading thereby allowing for the screw coupling of the liquid supply conduit to the shaft. This solution is effective as long as one is dealing with metal cutting tools having elongated tool shafts of fixed standard length. In many cases, however, and in order to allow for the ready mounting of the tool, it proves to be necessary to modify the length of the tool shaft by cutting away a portion thereof. This cutaway portion, of course, includes the threaded portion of the cooling duct and the thus modified cutting tool can no longer be readily screw coupled to the liquid supply conduit.
It has been proposed in Japanese published Utility Model Application No. 3-75912, to overcome this problem by fitting the mouth of the cooling duct with a tubular, internally threaded bushing into which a correspondingly threaded end of the supply conduit can be screw coupled. In this way, the conduit can be screw coupled to the elongated shaft even though the length of that shaft may have been modified and the mouth of the conduit is no longer provided with its own screw threading.
Whilst this proposal is relevant where the cutting tool is directly mounted on the machine tool turret and the cooling liquid supply conduit is directly coupled to the tool shaft, an entirely different problem arises where the cutting tool is mounted on the machine tool turret via an intermediate adaptor. In such a case the end of the tool shaft which includes the mouth of the cooling duct is received within the adaptor and the tool shaft is clamped to the adaptor. It is clearly not possible to couple the liquid cooling duct to the end of the tool shaft and the adaptor is provided with a cooling fluid entry port which communicates on the one hand with the cooling duct and, can be coupled on the other hand to the cooling supply conduit. Thus, the cooling liquid enters the adaptor and passes into the cooling duct. It is however clear that if the end portion of the tool shaft held within the adaptor is not sealingly fitted to the adaptor, cooling liquid will flow out of the adaptor around the walls of the tooling shaft. In practice, it is difficult and sometimes impossible to ensure a sealing fit of the tool shaft within the adaptor and this, particularly in view of the fact that the tool shaft which is of general circular cross-sectional shape, is formed with planar surface portions on which bear clamping screws which serve to clamp the adaptor to the tool shaft.
It is an object of the present invention to provide means for use with a liquid cooled metal cutting tool which overcomes the above-referred to problems, when the tool is mounted via an intermediate adaptor.